It is impossible to count the dead
- From: Lance <LanceGary@xxxxxxxxx>
- Date: Tue, 25 Mar 2008 06:20:20 -0700 (PDT)
NYT
March 25, 2008
Bats Perish, and No One Knows Why
By TINA KELLEY
Al Hicks was standing outside an old mine in the Adirondacks, the
largest bat hibernaculum, or winter resting place, in New York State.
It was broad daylight in the middle of winter, and bats flew out of
the mine about one a minute. Some had fallen to the ground where they
flailed around on the snow like tiny wind-broken umbrellas, using the
thumbs at the top joint of their wings to gain their balance.
All would be dead by nightfall. Mr. Hicks, a mammal specialist with
the state’s Environmental Conservation Department, said: “Bats don’t
fly in the daytime, and bats don’t fly in the winter. Every bat you
see out here is a ‘dead bat flying,’ so to speak.”
They have plenty of company. In what is one of the worst calamities to
hit bat populations in the United States, on average 90 percent of the
hibernating bats in four caves and mines in New York have died since
last winter.
Wildlife biologists fear a significant die-off in about 15 caves and
mines in New York, as well as at sites in Massachusetts and Vermont.
Whatever is killing the bats leaves them unusually thin and, in some
cases, dotted with a white fungus. Bat experts fear that what they
call White Nose Syndrome may spell doom for several species that keep
insect pests under control.
Researchers have yet to determine whether the bats are being killed by
a virus, bacteria, toxin, environmental hazard, metabolic disorder or
fungus. Some have been found with pneumonia, but that and the fungus
are believed to be secondary symptoms.
“This is probably one of the strangest and most puzzling problems we
have had with bats,” said Paul Cryan, a bat ecologist with the United
States Geological Survey. “It’s really startling that we’ve not come
up with a smoking gun yet.”
Merlin Tuttle, the president of Bat Conservation International, an
education and research group in Austin, Tex., said: “So far as we can
tell at this point, this may be the most serious threat to North
American bats we’ve experienced in recorded history. “It definitely
warrants immediate and careful attention.”
This month, Mr. Hicks took a team from the Environmental Conservation
Department into the hibernaculum that has sheltered 200,000 bats in
past years, mostly little brown bats (Myotis lucifugus) and federally
endangered Indiana bats (Myotis sodalis), with the world’s second
largest concentration of small-footed bats (Myotis leibii).
He asked that the mine location not be published, for fear that
visitors could spread the syndrome or harm the bats or themselves.
Other visitors do not need directions. The day before, Mr. Hicks saw
eight hawks circling the parking lot of another mine, waiting to kill
and eat the bats that flew out.
In a dank galley of the mine, Mr. Hicks asked everyone to count how
many out of 100 bats had white noses. About half the bats in one
galley did. They would be dead by April, he said.
Mr. Hicks, who was the first person to begin studying the deaths, said
more than 10 laboratories were trying to solve the mystery.
In January 2007, a cave explorer reported an unusual number of bats
flying near the entrance of a cavern near Albany. In March and April,
thousands of dead bats were found in three other mines and caves. In
one case, half the dead or living bats had the fungus.
One cave had 15,584 bats in 2005, 6,735 in 2007 and an estimated 1,500
this winter. Another went from 1,329 bats in 2006 to 38 this winter.
Some biologists fear that 250,000 bats could die this year.
Since September, when hibernation began, dead or dying bats have been
found at 15 sites in New York. Most of them had been visited by people
who had been at the original four sites last winter, leading
researchers to suspect that humans could transmit the problem.
Details on the problem in neighboring states are sketchier. “In the
Berkshires in Massachusetts, we are getting reports of dying/dead bats
in areas where we do not have known bat hibernacula, so we may have
more sites than we will ever be able to identify,” said Susi von
Oettingen, an endangered species biologist with the United States Fish
and Wildlife Service.
In Vermont, Scott Darling, a wildlife biologist with the Fish and
Wildlife Department, said: “The last tally that I have is
approximately 20 sites in New York, 4 in Vermont and 2 in
Massachusetts. We only have estimates of the numbers of bats in the
affected sites — more or less 500,000. It is impossible for us to
count the dead bats, as many have flown away from the caves and died —
we have over 90 reports from citizens across Vermont — as well as many
are still dying.”
People are not believed to be susceptible to the affliction. But New
Jersey, New York and Vermont have advised everyone to stay out of all
caverns that might have bats. Visitors to affected caves and mines are
asked to decontaminate all clothing, boots, ropes and other gear, as
well as the car trunks that transport them.
One affected mine is the winter home to a third of the Indiana bats
between Virginia and Maine. These pink-nosed bats, two inches long and
weighing a quarter-ounce, are particularly social and cluster together
as tightly as 300 a square foot.
“It’s ironic, until last year most of my time was spent trying to
delist it,” or take it off the endangered species list, Mr. Hicks
said, after the state’s Indiana bat population grew, to 52,000 from
1,500 in the 1960s.
“It’s very scary and a little overwhelming from a biologist’s
perspective,” Ms. von Oettingen said. “If we can’t contain it, we’re
going to see extinctions of listed species, and some of species that
are not even listed.”
Neighbors of mines and caves in the region have notified state
wildlife officials of many affected sites when they have noticed bats
dead in the snow, latched onto houses or even flying in a recent
snowstorm.
Biologists are concerned that if the bats are being killed by
something contagious either in the caves or elsewhere, it could spread
rapidly, because bats can migrate hundreds of miles in any direction
to their summer homes, known as maternity roosts. At those sites,
females usually give birth to one pup a year, an added challenge for
dropping populations.
Nursing females can eat up to half their weight in insects a day, Mr.
Hicks said.
Researchers from institutions like the Centers for Disease Control and
Prevention, the United States Geological Survey’s National Wildlife
Health Center, Boston University, the New York State Health Department
and even Disney’s Animal World are addressing the problem. Some are
considering trying to feed underweight wild bats to help them survive
the remaining weeks before spring. Some are putting temperature
sensors on bats to monitor how often they wake up, and others are
making thermal images of hibernating bats.
Other researchers want to know whether recently introduced pesticides,
including those released to stop West Nile virus, may be contributing
to the problem, either through a toxin or by greatly reducing the
bat’s food source.
Dr. Thomas H. Kunz, a biology professor at Boston University, said the
body composition of the bats would also be studied, partly to
determine the ratio of white to brown fat. Of particular interest is
the brown fat between the shoulder blades, known to assist the bats in
warming up when they begin to leave deep hibernation in April.
“It appears the white nose bats do not have enough fat, either brown
or white, to arouse,” Dr. Kunz said. “They’re dying in situ and do not
have the ability to arouse from their deep torpor.”
His researchers’ cameras have shown that bats in the caves that do
wake up when disturbed take hours longer to do so, as was the case in
the Adirondack mine. He also notes that if females become too
emaciated, they will not have the hormonal reactions necessary to
ovulate and reproduce.
In searching for a cause of the syndrome, researchers are hampered by
the lack of baseline knowledge about habits like how much bats should
weigh in the fall, where they hibernate and even how many bats live in
the region.
“We’re going to learn an awful lot about bats in a comprehensive way
that very few animal species have been looked at,” said Dr. Elizabeth
Buckles, an assistant professor at Cornell who coordinates bat
research efforts. “That’s good. But it’s unfortunate it has to be
under these circumstances.”
The die-offs are big enough that they may have economic effects. A
study of Brazilian free-tailed bats in southwestern Texas found that
their presence saved cotton farmers a sixth to an eighth of the cash
value of their crops by consuming insect pests.
“Logic dictates when you are potentially losing as many as a half a
million bats in this region, there are going to be ramifications for
insect abundance in the coming summer,” Mr. Darling, the Vermont
wildlife biologist, said.
As Mr. Hicks traveled deeper in the cave, the concentrations of bats
hanging from the ceiling increased. They hung like fruit, generally so
still that they appeared dead. In some tightly packed groups, just
individual noses or elbows peeked through. A few bats had a wing
around their nearest cavemates. Their white bellies mostly faced
downhill. When they awoke, they made high squeaks, like someone
sucking a tooth.
The mine floors were not covered with carcasses, Mr. Hicks said,
because raccoons come in and feed on them. Raccoon scat dotted the
rocks along the trail left by their footprints.
In the six hours in the cave taking samples, nose counts and
photographs, Mr. Hicks said that for him trying for the perfect
picture was a form of therapy. “It’s just that I know I’m never going
to see these guys again,” he said. “We’re the last to see this
concentration of bats in our lifetime.”
.
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